Coll and Tiree Proposed Special Protection Area (Pspa) NO

Coll and Tiree Proposed Special Protection Area (pSPA) NO. UK9020310

SPA Site Selection Document: Summary of the scientific case for site selection

Document version control

Version and Amendments made and author Issued to date and date Version 1 Formal advice submitted to Marine Scotland on Marine draft SPA. Nigel Buxton & Greg Mudge. Scotland 10/07/14 Version 2 Updated to reflect change in site status from draft Marine to proposed and addition of SPA reference Scotland number in preparation for possible formal 30/06/15 consultation. Shona Glen, Tim Walsh & Emma Philip Version 3 Creation of new site selection document. Emma Susie Whiting Philip 17/05/16 Version 4 Document updated to address requirements of Greg revised format agreed by Marine Scotland. Mudge Emma Philip 22/06/16 Version 5 Quality assured Emma Greg Mudge Philip 22/6/16 Version 6 Final draft for approval Andrew Emma Philip Bachell 23/06/16 Version 7 Final version for submission to Marine Scotland Marine Scotland 24/06/16

Contents

1. Introduction ...... 1 2. Site summary ...... 2 3. Bird survey information ...... 4 4. Assessment against the UK SPA Selection Guidelines ...... 4 5. Site status and boundary ...... 10 6. Information on qualifying species ...... 10 7. References ...... 14 Annex 1. Site map ...... 15 Annex 2. Citation ...... 16

1. Introduction

This document provides Scottish Natural Heritage’s (SNH) advice on the proposed classification of a Special Protection Area (SPA) in the marine waters of “Coll and Tiree” for inshore wintering waterfowl. It summarises the evaluation for each of the species of interest according to the SPA site selection guidelines (JNCC, 1999) and provides an overview of how the site boundary was developed.

Coll and Tiree has been selected to provide protection to important wintering grounds used for feeding, moulting and roosting by non-breeding great-northern diver and common eider. The protection of these inshore waters will make a key contribution to the maintenance of these species in their natural range in UK marine waters and form part of a coherent network of sites at a European level.

The importance of the marine environment for birds which spend all or part of their lives around our coasts is well recognised, particularly in Scotland. A total of 106 species of bird are thought to use UK marine waters of which 45 occur in numbers greater than fifty each year and are dependent on the marine environment for a large part of their lifecycle. All of these 45 species except one (black guillemot1) are considered rare or vulnerable bird species (Annex 1), or regularly occurring migratory species by the Birds Directive (EC Directive on the conservation of wild birds (amended) - 2009/147/EC). This means that all Member States are obliged to take account of the requirements of Article 4.1 of the Birds Directive for each of these 44 species.

Article 4.1 states that “Member States shall classify in particular the most suitable territories in number and size as special protection areas for the conservation of these species, taking into account their protection requirements in the geographical sea and land area where this Directive applies”. European Commission guidance on the establishment of SPAs in the marine environment (2007) sets out the groups of marine birds for which SPAs should be considered in the marine environment. This includes sites for wintering waterfowl.

In the UK, whilst some coastal SPAs include marine waters below the Mean High Water Springs (MHWS) there are only four entirely marine SPAs classified; Outer Thames Estuary SPA (England), Liverpool Bay/Bae Lerpwl SPA (England/Wales) and Bae Caerfyrddin/Carmarthen Bay SPA (Wales) and Belfast Lough - Open Water SPA (Northern Ireland). In Scotland, 31 marine extensions to seabird colony SPAs have also been classified. The existing suite of sites is not considered sufficient to meet the requirements of Article 4.1 because it currently does not include suitable territories at sea for all of the species that the UK has a responsibility for.

The marine waters of Coll and Tiree are being proposed as part of a suite of marine sites that aim to fulfil the requirements for SPAs in the marine environment for rare or vulnerable birds and regularly occurring migratory birds in the UK. As required by Article 4 of the Directive, the classification of this site will enable the application of

1 Nature Conservation Marine Protected Areas were designated in August 2014 for black guillemot.

1 special conservation measures concerning the habitat of Annex 1 and regularly occurring migratory birds in order to ensure their survival and reproduction in their area of distribution.

Full details of the site survey methodologies, data and analysis used to inform the proposed selection of this site are provided in Lawson et al (2015). All scientific work received full external independent peer review at key stages.

2. Site summary

The Coll and Tiree proposed Special Protection Area largely surrounds the closely adjacent islands of Coll and Tiree off the coast of Argyll.

The site supports a population of European importance of the following Annex 1 species:

 Great northern diver (Gavia immer)

It also supports a migratory population of European importance of the following species:

 Common eider (Somateria mollissima)

Coll and Tiree lie relatively close to the mainland coast of Argyll and the island of Mull (less than 15 kilometres (km) away) in a north-east/south-west direction. Parts of the coastline of Coll are rocky interspersed with extensive sandy bays and soft shores whilst Tiree has an even greater extent of sandy beaches and machair (Barne et al. 1997). Offshore of both islands the sediments are consequently a mixture of mud, sand and gravel. The waters immediately offshore are shallow, generally less than 20 metres (m) in depth, with depth only increasing steadily to 120m some distance off the western shores, forming excellent habitat for over wintering waterfowl.

A wide variety of pelagic and demersal fish occur in the marine habitats around the islands as well as many invertebrates including both crustaceans and bivalve molluscs, all of which form potential prey for marine waterbirds.

Great northern divers feed on a wide variety of fish as well as opportunistically on crustaceans. They are capable of diving to considerable depths with figures of 55m recorded in pursuit of their prey underwater (Ropert-Coudert et al 2016). The fish species taken will be influenced by what is locally most readily available, but can include haddock Melanogrammus aeglefinus, cod Gadus morhua, herring Clupea harengus, sprats Sprattus sprattus and gurnard Eutrigla gurnardus along with smaller species such as sand-eels Ammodytidae, pipefish Syngathidae, gobies Gobiidae, flatfish Pleuronectidae and butterfish Pholis gunnellus.

Common eider feed almost exclusively on molluscs and small crustaceans, diving from the surface to pluck their prey from the seabed.

Eider more typically feed at depths not exceeding 15m.

Great northern divers are long distance migrants, moving annually between northern breeding grounds and more southerly wintering grounds such as those in the Coll and Tiree pSPA. Eider are resident in this area throughout the year.

Figure 1. Location of Coll and Tiree pSPA

3. Bird survey information Inshore aggregations of non-breeding waterfowl

Areas of search Existing data (including Wetland Bird Surveys (WeBS), Important Bird Areas (IBA) under BirdLife International, existing survey data and an atlas of seabird distributions) and information from published scientific literature were used to determine which initial areas might be important for inshore wintering waterfowl. Based on this initial assessment, 46 areas of search were identified across the UK, with 22 of these in Scotland. An area encompassing the entire Coll and Tiree pSPA was one of the areas of search identified as holding potentially large numbers of birds and therefore merited further survey.

Aerial transect (2003/04-2007/08) Line transect aerial surveys were carried out on six occasions on 18th February 2004, 26th March 2005, 10 and18th February 2006, 21st March 2006, 24th March 2007,and 17th March 2008. All of these surveys were conducted by the Joint Nature Conservation Committee (Lawson et al 2015). Surveys were conducted between November and March to enable estimates of non-breeding populations to be made. No data were collected during migration periods or for aggregations of moulting birds.

The data from the aerial transect surveys were used to produce density distribution maps and population estimates for great northern diver and common eider.

Estimating numbers of birds within an SPA boundary SPA boundaries were drawn only for those species which occurred in qualifying numbers in the area of search (section 4) and for which suitable aerial survey data were available (section 5). ArcGIS was used to calculate the area [km2] of each 1km x 1km cell, or partial cell, located within the new boundary. For each grid cell the total number of individuals for each species was then estimated by multiplying the cell area with the species densities within each individual cell. The total of individuals for each species within the new boundary was provided by summing all cell totals within the boundary by species and season.

The number of birds within the SPA boundary was then reassessed against the UK SPA Selection Guidelines to ensure the site still qualified for consideration as an SPA.

4. Assessment against the UK SPA Selection Guidelines

The UK SPA Selection Guidelines establish a two stage process for SPA identification (JNCC, 1999). Stage 1 allows identification of areas that are likely to qualify for SPA status.

Stage 1

To qualify under Stage 1 the area needs to meet one or more of the following four guidelines:

1.1. The area is used regularly by 1% or more of the Great Britain population of a species listed in Annex I to the Birds Directive in any season. 1.2. The area is used regularly by 1% or more of the biogeographical population of a regularly occurring migratory species (other than those listed in Annex I) in any season. 1.3. The area is used regularly by over 20,000 waterbirds (waterbirds as defined by the Ramsar Convention) or 20,000 seabirds in any season. 1.4. The area meets the requirements of one or more of the Stage 2 guidelines in any season, where the application of Stage 1 guidelines 1.1-1.3 for a species does not identify an adequate suite of most suitable areas for the conservation of that species.

Stage 2

Those areas that meet one or more of the Stage 1 guidelines undergo further consideration using one or more of the ecological judgements set out in Stage 2. There are seven Stage 2 judgements. These judgments are used to facilitate the selection of the most suitable areas from the areas identified at Stage 1 to produce a network of marine SPAs in Scotland. The Stage 2 judgements are:

2.1 Population size and density 2.2 Species range 2.3 Breeding success 2.4 History of occupancy 2.5 Multi-species area 2.6 Naturalness 2.7 Severe weather refuges

Application of Stage 1.4

Ten species of non-breeding migratory waterfowl and seabirds (non-Annex 1) frequently occur in Scottish marine waters in substantial numbers. All of these species have very large biogeographic populations often spread over extensive areas. This means that applying guideline 1.2 (area regularly used by 1% or more of the biogeographical population of a regularly occurring migratory species), which has been helpful in identifying important areas on land, would largely fail to identify important areas at sea for these non-breeding migratory species. It is SNH and JNCC’s view that the absence of these species from a suite of marine SPAs would not satisfy the requirements of Article 4.1 of the Birds Directive.

Therefore, to ensure these species are represented they were considered using guideline 1.4. This is specifically designed to capture cases where a species' population status, ecology or movement patterns may mean that an adequate number of areas cannot be identified from guidelines 1.1-1.3 alone.

Our experience is that marine bird ‘hotspots’ usually support several species in substantial numbers potentially resulting in an SPA with rich biodiversity. In applying this fourth guideline, SNH only considered sites that had already been identified as potential SPAs for one or more species using guidelines 1.1-1.3. This approach allows for all ten species of non-breeding migratory birds (non-Annex 1) to be represented in the proposed SPA suite. Without prejudice to any forthcoming review of marine SPA sufficiency, our view is that inclusion of these species in the proposed suite will provide an adequate number of areas for these species.

To assess which sites may be considered as suitable areas for those migratory birds that did not meet the threshold of 1% or more of their bio-geographical population, SNH focused on three of the Stage 2 judgments (population size and density, species range and multi-species area).

To provide a consistent and quantifiable population threshold for species that may be considered using guideline 1.4, species only became candidates for inclusion in a site where they occurred in numbers in excess of 1% of their Great Britain (GB) population. This population threshold is consistent with the population threshold used to identify named qualifiers of a waterbirds or seabird assemblage selected under guideline 1.3.

At this pSPA, common eider have been identified using this approach (>1% GB population), each with a high proportion of their distribution overlapping qualifying Annex 1 species. The approach has been reviewed and supported by SNH’s Scientific Advisory Committee.

Assessment against Stage 1 of the UK SPA Selection Guidelines

Great northern diver is an Annex 1 species and was present in numbers at or above 1% of the GB population. This species met Stage 1.1 of the SPA guidelines (Table 1).

Common eider are a regularly occurring migratory species that did not occur in numbers at or above 1% of their biogeographical populations and therefore did not meet Stage 1.2 of the guidelines. It did however exceed 1% of the GB population and could therefore be considered under Stage 1.4 (Table 1).

Table 1. Assessment against Stage 1 of the UK SPA Selection Guidelines

Species and season Annex 1 Population % of GB Stage 1 or size in site population guideline migratory Great northern diver Annex 1 452 18.1 1.1 (winter) Common eider (winter) Migratory 1465 2.4 1.4

Assessment against Stage 2 of the UK SPA Selection Guidelines

One or more of the Stage 2 guidelines are used to identify the most suitable areas for classifying as SPA from those areas that meet the Stage 1 guidelines. The focus for considering which areas were most suitable concentrated on three of the seven judgements; population size and density, species range and multi-species areas. Population densities were only considered for non-breeding Annex 1 species.

Fourteen areas around Scotland (from the initial 22) were identified as meeting Stage 1.1 for non-breeding Annex 1 species, including great northern diver. To help identify the most suitable sites for SPAs from the initial 14 areas, the non-breeding Annex 1 species were ranked for each site according to their population size, density and number of other non-breeding qualifying species also present within each area. Particular emphasis was placed on identifying areas that function as “hotspots” for many species rather than just a few. The results of the ranking exercise for the Coll and Tiree are provided in Table 2.

Table 2: Summary of initial Annex 1 ranking and overlapping multi-species interest for inshore non-breeding waterbirds

Assessment/ Ranked importance for non-breeding Annex 1 Qualifying feature species 2 Great northern diver 8th most important site in Scotland Black-throated diver Not qualifying Red-throated diver Not qualifying Slavonian grebe Not qualifying

While ranked 8th overall for great northern diver Coll and Tiree supports the 4th largest non-breeding population of this Annex 1 species in Scotland, representing over 18% of the GB wintering population. This site also represents an important component of the species’ range. Additionally, this site supports significant numbers of eider.

Stage 2 judgements were also assessed for the other non-breeding (non-Annex 1) species considered at stage 1.4 on the basis of their populations exceeding 1% of the GB population (common eider) to ensure it was appropriate to include these species within the Coll and Tiree site (Table 3). This analysis supported the value of this area, particularly given its location in Scotland.

With regard to the other Stage 2 judgements, all sites were considered largely ‘natural’, judgements on breeding success was irrelevant for inshore wintering waterfowl and no information was available to provide further consideration to ‘severe weather refuge’.

2 Ranking was only applied to non-breeding Annex 1 species to provide an initial short-listing of most suitable areas that could then be subject to further checks for other marine bird interests. Ranking combines population size, density and multi-species interest to provide an overall rank. 7

Further details on the selection process and the final suite of sites being proposed is provided in the SNH supplementary document ‘Site selection of the marine SPA suite’ (SNH, 2016).

Table 3: Summary of assessment against Stage 2 of the UK SPA Selection Guidelines. nb = non-breeding

Stage 2 judgement/ Population size3 Species range Influence on site boundary? Qualifying features Great northern 4th largest Representative of the south- Pre-dominate species influencing diver (nb) population in western range in GB. seaward boundary Scotland. Common eider (nb) 6th largest Important component of the Almost complete overlap with great population in western range in Scotland. northern diver with a marginal Scotland. influence north of Tiree. Stage 2 judgement (whole site) Multi- Nationally important numbers of two species, of which great northern diver is on Annex 1, occur species regularly within this pSPA in the winter months. area History of Great northern divers and eiders have been known to frequent the west coast of Scotland for almost occupancy 200 years (Gray 1871, Lack 1986).

3 Population sizes are taken from Lawson et al 2015 9

5. Site status and boundary

The proposed name for this site is the “Coll and Tiree SPA”.

An SPA boundary, identified on the basis of numbers and distribution of great northern divers, also encompasses a substantial proportion of the population of common eider. A mean density surface was produced for great northern diver and common eider and a boundary drawn around a threshold density as determined by maximum curvature analysis (Lawson et al loc. cit.) . The threshold densities identified by maximum curvature were: 0.38 birds.km-2 (great northern diver) and 0.72 birds.km-2 (common eider).

The proposed site extends to 794.75 km2. Boundary co-ordinates for the pSPA are given on the pSPA map in Annex 1.

6. Information on qualifying species

Great northern diver Great northern divers were widely distributed round the majority of the coastlines of both Coll and Tiree (Figure 2). Numbers exceeded the Stage 1.1 threshold of 1% of the Great Britain population and the default site selection threshold of 50 birds (species with small or poorly quantified populations) on all six aerial line transect surveys between February 2004 & March 2008. The maximum population estimate of 1172 birds was in February 2004. Overall the species meets the definition of regularly occurring and has a mean of peak annual wintering population estimate of 452 birds (18.1% of the current Great Britain population estimate).

Population size and density This is one of the four largest populations of great northern divers (452 birds) in Scotland and, as one of the three large west coast populations, holds more than 18% of GB’s birds. Densities within the proposed site range between 0.1 birds/km2 and 3.0 birds/km2, with much of the pSPA supporting the higher densities.

Distribution within the site Great northern diver was the main species influencing the extent of the proposed boundary and are distributed throughout the site (Figure 2).

Species range The species occurs during winter round much of the UK coastline. The northern and western seaboards of Scotland are the winter strongholds of the GB great northern diver population. Numbers are sparse or local south of Duncansby Head in Caithness and around the Clyde estuary. The west of Ireland, and to a considerable degree its south coast, are also important. This pSPA is important in representing the south-western part of the range in Scotland.

History of occupancy Great northern divers have been known to frequent the locality for almost 200 years (Gray 1871, Baxter & Rintoul 1953).

Figure 2. The distribution of great northern divers around Coll and Tiree pSPA.

Common eider Numbers did not exceed those needed to meet the Stage 1.2 guideline (10,300 birds) but considerably exceeded the level of 1% of the Great Britain total (600 birds Lawson 2014) in five out of the six aerial surveys conducted between February 2004 and March 2008. In most years the population estimate was around 1,000 birds but the maximum estimate in February 2004 was approximately 3,000. Overall the mean peak annual wintering population for the years of 2003/04 to 2007/08 was 1,465 birds (2.4 % of the GB population).

Population size and density For a species which has a very sizeable biogeographic population of about 1,030,000 birds (Wetlands International 2014) no location in Great Britain reaches the 1% selection level to meet the Stage 1.2 Guideline. Nevertheless Great Britain supports a large national population, with most distributed throughout Scotland. Hence, a mean of peak estimates population of 1,465 birds (2.4% of the Great Britain population), distributed substantially in the same area as great northern diver (Figure 3) identifies the Coll and Tiree pSPA as an important site meeting the SPA Site Selection Guideline 1.4. Only the west coasts of the Outer Hebrides and the Firth of Clyde on the west coast support larger numbers.

Density estimates range from <0.2 – 13.0 birds/km2 comparable with those on the West Coast of the Outer Hebrides but lower than maxima in the Firths of Tay and Forth where there are sizeable local breeding colonies.

Distribution within the site The common eider distribution is concentrated mostly around Tiree and the south- west coast of Coll. There is considerable overlap with the distribution of great northern diver (Figure 3).

Species range Whilst eiders are widely distributed and, during winter, may occur round virtually the whole coastline of Great Britain the range is predominantly in northern England and especially mainland Scotland and the Scottish island groups. The sea off Coll and Tiree is one of the main winter concentrations in Scotland, especially off the west coast of Scotland.

History of occupancy Common eiders have been known to frequent the locality for almost 200 years (Baxter & Rintoul 1953).

Figure 3. The distribution of common eiders around the Coll and Tiree pSPA.

7. References

Barne, J. H., Robson, C. F., Kaznowska, S. S., Doody, J. P. Davidson, N. C. & Buck, A. L. eds 1997. Coasts and seas of the United Kingdom. Regions 14 South-west Scotland: Ballantrae to Mull. Peterborough, Joint Nature Conservation Committee. (Coastal Directories Series.)

Baxter, E. V. & Rintoul, L. J. 1953. The birds of Scotland : their history, distribution, and migration. Edinburgh, Oliver and Boyd.

European Commission (2007) Guidelines for the establishment of the Natura 2000 network in the marine environment. Application of the Habitats and Birds Directives. http://ec.europa.eu/environment/nature/natura2000/marine/docs/marine_guidelines.p df

Forrester, R. & Andrews, I. 2007. The Birds of Scotland. SOC

Gray R. 1871. The Birds of the West of Scotland; Including the Outer Hebrides, with Occasional Records of the Occurrence of the Rarer Species Throughout Scotland Generally

JNCC. 1999. The Birds Directive. Selection Guidelines for Special Protection Areas. Peterborough, JNCC. 6pp.

JNCC generic documents: Identification of important marine areas for inshore wintering waterbirds

Lack, P. 1986. The Atlas of Wintering Birds in Britain and Ireland. Calton, T & A.D. Poyser.

Lawson, J., Kober, K., Win, I., Bingham, C., Buxton, N.E., Mudge, G., Webb, A., Reid, J.B., Black, J., Way, L. & O’Brien, S. 2015. An assessment of numbers of wintering divers, seaduck and grebes in inshore marine areas of Scotland. JNCC Report No 567. JNCC, Peterborough.

Musgrove, A., Aebischer,, N Eaton, M., Hearn, R., Newton, S Noble S., Parsons, M., Risely, K. & Stroud, D. 2013. Population estimates of birds in Great Britain and the United Kingdom. British Birds 106; 64-100.

Ropert-Coudert, Y., Bertho, Y., Kato A. and Martin, A (2016) penguiness book (http://penguinessbook.scarmabin.be) accessed 02-06-2016

SNH 2016. ‘Site selection of the marine SPA suite’. Supplementary document.

Wetlands International ( 2014). "Waterbird Population Estimates" . Retrieved from wpe.wetlands.org on Friday 18 Apr 2014

Annex 1. Site map

Annex 2. Citation

Directive 2009/147/EC of the European Parliament and of the Council on the conservation of wild birds (this is the codified version of Directive 79/409/EEC as amended)

CITATION FOR PROPOSED MARINE SPECIAL PROTECTION AREA (SPA)

COLL AND TIREE (UK9020310)

Site Description: The Coll and Tiree proposed Special Protection Area largely surrounds the closely adjacent islands of Coll and Tiree off the coast of Argyll. Both islands have rocky coastlines with extensive areas of soft shores. Offshore of both islands the sediments are consequently a mixture of mud, sand and gravel. The waters immediately offshore are shallow, generally less than 20m in depth, only increasing steadily to 120m some distance off the western shores. Supporting a diversity of fish and invertebrates the seas off both islands form excellent habitat for over wintering waterfowl.

Qualifying Interest: The Coll and Tiree proposed Special Protection Area (SPA) qualifies under Article 4.1 by regularly supporting a wintering population of European importance of the following Annex 1 species: great northern diver Gavia immer (a mean peak annual wintering population of 460 individuals, 18.4% of the Great Britain population) for the years of 2003/04 to 2007/08).

The site further qualifies under Article 4.2 by regularly supporting populations of European importance of the following migratory species: common eider Somateria mollissima (a mean peak annual wintering population of 1,465 individuals, 2.4% of the GB population) for the years of 2003/04 to 2007/08).

Area: 794.75 km2 (79,475.15 ha). Location: 56o 60.025’ N 6o 76.951’ W OS Sheet 1:50,000 – 46 & 47

22/06/16 Scottish Natural Heritage